In the selective catalytic hydrogenation of crotonaldehyde using platinum-metal-type catalysts to obtain n-butyraldehyde, losses of about 5% arise due to the formation of carbon monoxide and propylene. These disadvantages are avoided by the process of DAS .differential.German Published Application] 1,070,160 (=U.S. Pat. No. 2,930,765 and U.S. Pat. No. 2,930,766) hy using metal catalysts of the platinum group on supports having a slightly alkaline activity. The selective hydrogenation of crotonaldehyde to n-butyraldehyde in this process takes place in the gaseous phase under normal pressure. However, only unsatisfactory space-time yields are obtained.
Therefore, there is great interest in providing an improved method for the selective hydrogenation of crotonaldehyde with higher space-time yields.